Staples

ABSTRACT

An improved surgical staple is disclosed wherein predetermined regions of the staple legs are weakened to cause bending and deformation of said legs in a controlled manner. The staple provides a uniform compression of a tissue into which it is inserted.

The present application is a rule 1.60 continuation of application Ser.No. 08/024,501 filed Mar. 2, 1993, now U.S. Pat. No. 5,342,396.

TECHNICAL FIELD

This invention relates to stapling and, more particularly, to improvedstaples for use in surgery and in other fields.

BACKGROUND OF THE INVENTION

Staples have a variety of uses. For example, surgeons use thin wirestaples to join the cut ends of hollow organs or ducts (anastomosis) andto achieve hemostasis. Thin wire staples are made by deforming a lengthof thin wire with uniform cross section and material properties to aU-shape. FIG. 1 shows a common prior art thin wire staple 100, includinga crown 101 and two legs 102. The staple shown in FIG. 1 has uniformcross section and material properties, except as these may be altered inthe region where the staple legs join the crown during deformation ofthe wire to the U-shape. Surgical staples are made of materials inert toattack by body fluids, e.g., stainless steels.

When a staple is installed, its legs are pushed into the material beingstapled. During installation, some staples are deformed, i.e., bent pasttheir elastic limit to achieve a permanent change in shape.

FIG. 2 shows the staple of FIG. 1 deformed to a B-shape duringinstallation due to its legs having being forced against an anvil withchannels to direct the legs as they bend and deform. This anvil islocated on the side of the material being stapled that is opposite tothe side into which staple insertion is made. The deformation of thestaple of FIG. 1 occurs in its leg region at and near the legs' juncturewith the crown, since this is where the maximum bending stress develops.

FIG. 2 shows that the separation of different locations on the legs 102from the crown 101 varies for a B-shaped staple. Thus, when B-shapedstaples are used in surgery, tissues located between different regionsof the legs and the crown undergo different compressions, and tissuecompression varies in the vicinity of the gap between leg ends whenthese ends are not in close proximity.

To achieve hemostasis using staples, the tissue compressed least by thestaples must still be compressed sufficiently for the hemostasis despitethe possibility that the tissue compressed most may be perforated ordamaged due to excessive compression or distortion. Necrosis, additionalscar tissue formation and longer healing times can result from excessivecompression or distortion. Shrinkage of scar tissue over time can leadto adverse results, and thus it is important to avoid forming more scartissue than necessary.

If the curvature of the staple legs where they join the crown is large,i.e., if the staple has a small radius at the junctures of the legs andthe crown, then the separation between the legs and the crown will besmall, and tissue may undergo excessive compression. If the curvature issmall, i.e., if the staple has a large radius at the junctures of thelegs and the crown, then tissue distortion may be excessive in thevicinity of the junctures.

It is an object of the present invention to provide a staple whichachieves uniform compression of stapled material.

It is also an object of the present invention to provide a surgicalstaple which minimizes scar tissue formation.

It is a further object of the present invention to provide a staplewhich minimizes distortion of the material stapled.

It is an additional object of the present invention to provide asurgical staple which minimizes healing time.

It is a further object of the present invention to provide a staplewhich minimizes damage of material stapled.

SUMMARY OF THE INVENTION

The above cited problems and others are overcome and the objects of theinvention are achieved in accordance with an improved staple whoseresistance to deformation in predetermined regions is so weakened thatdeformation during installation preferentially occurs in saidpredetermined regions although in the absence of such weakeningdeformation would not otherwise preferentially occur in saidpredetermined regions. Such predetermined regions with weakenedresistance to deformation are hereinafter termed "deformation zones".Deformation zones may be formed by reducing the minimum moment ofinertia, I, of the staple cross section in the deformation zone, byreducing the modulus of elasticity, E, of the staple material, or bymechanically supporting the staple so that maximum bending stress occursat the point of such support.

In the preferred embodiment of the inventive staple, the staple has twolegs, and each leg has a deformation zone in a predetermined region thatis separated from the staple crown by a leg region with greaterresistance to deformation than that of the deformation zone under thestress generated when the staple encounters an anvil duringinstallation, so that the staple preferentially deforms in thedeformation zone.

During installation, the inventive staple is, preferably, deformed to arectangular shape with rounded corners. This helps to achieve uniformcompression and to minimize distortion of the stapled material.

FIG. 1 depicts a prior art staple before installation;

FIG. 2 shows the prior art staple of FIG. 1 after being deformed to aB-shape;

FIG. 3 depicts an exemplary embodiment of the inventive staple;

FIG. 4 shows the staple of FIG. 3 after being deformed to a rectangularshape;

FIG. 5 shows exemplary cross sectional views (not to the scale of FIG.3) of possible deformation zone and adjacent leg regions for the stapleof FIG. 3;

FIG. 6 shows a double staggered staple line;

FIG. 7 is a partial front view in section of a first type of exemplaryanvil;

FIG. 8 is a partial front view in section of a second type of exemplaryanvil;

FIG. 9 is an alternative embodiment of the invention for use on materialwith varying thickness;

FIG. 10 depicts a loaded strip of staples for use with the invention;

FIG. 11 shows an alternative embodiment of the present invention whereinthe deformation zones are formed simultaneously with the installation ofthe staples; and

FIG. 12 shows the embodiment of FIG. 11 in use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A deformation zone is created by weakening the staple in a predeterminedregion so that deformation preferentially occurs in that region duringstaple installation. As is well-known in the art, the resistance todeformation of a region of a staple under stress is dependant on themagnitudes of its modulus of elasticity, E, in the region and the momentof inertia, I, of the minimum section including the axis around whichthe staple bends in the region. Reducing these quantities in a regionreduces the stress needed to deform a staple in that region. It isusually easier to reduce I than E.

Deformation zones should not be formed by weakening the staple in thepredetermined regions in such a manner as to result in staple failure,i.e., breakage, during staple deformation. For example, the improper useof sharp notches to form deformation zones can result in staple failure.

The legs of the inventive staple should be matched to the requirementsof the material stapled. That is, the locations of the deformation zonesshould be matched to the thickness of the material being stapled and tothe compression desired, and the staple leg lengths should be sized tobring the legs ends into close proximity. While such matching mayrequire the availability of multiple staples, this is justifiable whenthe compression achieved and its uniformity are important.

FIG. 3 shows an exemplary staple 300 in accordance with the presentinvention. The staple 300 includes a crown 301 and two legs 302. Eachleg 302 has a deformation zone 305 with weakened resistance to bendinginto direction 304 as compared to the resistance of leg regions 306 and307 which lie outside of the deformation zone 305. When the staple 300is subjected to stresses arising from forces acting in the direction304, the legs will bend into that direction, so that bending anddeformation will take place preferentially in deformation zone 305.

In FIG. 4, the staple of FIG. 3 is shown deformed into a rectangularshape. Material stapled with the staple of FIG. 3 will be under moreuniform compression than is the case with the B-shaped staple of FIG. 2.FIG. 4 reveals that the location and length of deformation zone 305 andthe length of the staple leg 302 are important leg parameters inobtaining a desired compression for stapled material of a particularthickness and in bringing the staple leg ends into close proximity. Thelength of leg region 306 between the crown 301 and the deformation zone305 should be matched to the requirements set by the combination of thethickness of the material being stapled and the compression of thismaterial that is desired. The length of leg region 307 between thedeformation zone 305 and the leg end 308 should be selected such thatthe separation of the leg ends 308 of the deformed staple is minimizedwithout interference between the leg ends 308 occurring as the staple isdeformed during installation.

A comparison of FIG. 2 and FIG. 4 reveals that material stapled with thestaple 300 of FIG. 3 will be less distorted and under more uniformcompression than occurs with B-shaped staples.

In FIG. 5, exemplary cross sections (not shown to the scale of FIG. 3)are shown for the legs 302 of the staple 300 of FIG. 3. In FIG. 5 (a),.a cross section for regions of the staple legs 302 outside thedeformation zone 305 is shown. In FIG. 5 (b) and (c), two differentpossible cross sections for the staple leg cross section in thedeformation zone 305 are shown. The values of I for the staple leg indeformation zones with the cross sections shown in FIG. 5 (b) or (c) forbending into direction 304 are less than if they had the cross sectionof FIG. 5 (a).

In FIG. 6, a double staggered staple line 600 formed from inventivestaples 300 of FIG. 4 is shown, each row being offset with respect tothe other row. Surgeons make use of double staggered staple lines, e.g.,to compress tissue for hemostasis at the cut end of an organ or toperform an anastomosis. The present staples thus have application inhemostasis and anastomosis, for example.

In FIG. 7, a cross section is shown of an anvil 700 for use with thestaple of FIG. 3 to produce the deformed staple of FIG. 4. Channels 701formed in the anvil 700 direct bending and deformation of staple legs302 when staple 300 is forced against anvil 700 and the legs 302encounter the anvil 700. Anvil 700 is stationary as the staple 300 isforced against it.

In FIG. 8, an anvil 800 alternative to that of FIG. 7 for use with thestaple 300 of FIG. 3 is shown. The legs 302 of the staple 300 encounterchannels 801 of anvil 800 after penetrating through the material beingstapled (not shown in FIG. 8). Anvil 800 moves towards the staple 300 asthe staple 300 is forced against the anvil 800. This motion of the anvilmay be accomplished using means well known to the art. The motion of theanvil minimizes distortion of the material being stapled by the staplelegs 302 as they bend and deform.

It should be noted that the legs 302 after the staple 300 is deformed,as shown in FIG. 4, do not conform to the shape of the channel 701.Rather, the end 308 of leg 302 follows the shape of the channel 701until the leg regions 306 and 307 are bent at angles (preferably, atright angles) to one another. The stapler may include a stop (702, 802)to prevent staple bending beyond the desired amount, although such astop is not required for the installation of a staple. An exemplary stop(702, 802) is shown, but other techniques using means well known in theart can be employed to prevent the stapler jaws from closing too much sothat staples are deformed beyond desired points.

Although stapler jaws are usually parallel to each other when thethickness of the material being stapled is uniform, material thicknesssometimes varies over a length where a stapler line is to be inserted.In FIG. 9, an alternative staple jaws arrangement 900 is shown whichincludes two stapler jaws 901 and 902 which are slanted with respect toeach other. (Stapler jaw 902 functions as an anvil.) This embodiment canbe used if the thickness of the material being stapled varies over thelength of a line of staples that the surgeon wishes to insert.

In order to maximize the benefits of the present invention and toachieve a good result, the upper jaw 901 is slanted with respect to thelower jaw 902, as shown. As a result, the separation of the stapler jaws901 and 902 varies in correspondence with the variation in the thicknessof the material (not shown in FIG. 9) being stapled.

The individual staples used with the arrangement of FIG. 9 would haveleg deformation zones located differently with respect to each other inorder to accommodate the different thicknesses of the material beingstapled. Specifically, it can be seen from FIG. 9 that the staplecontacting channel 903 should have shorter leg lengths between its legdeformation zones and the staple crown than should the staple contactingchannel 904. Additionally, the leg lengths of the staple used at channel903 may be less than the leg lengths of the staple used at channel 904.

It is possible for the staples to be manufactured with uniform crosssections and material properties, and for the deformation zones to beformed by the surgeon by modifying the staples just prior to use so thatthey correspond to the requirements of the material being stapled. Forexample, the surgeon could notch or file the staple legs to create thedeformation zones, and/or cut the staple legs to desired lengths.Devices which can be used for such purposes can use means well known inthe art. Such an approach would reduce the size of staple inventoryrequirements.

FIG. 10 shows a loading strip 1001 carrying prior art staples 100. Theloading strip 1001 can be placed into a device (not shown in FIG. 10)which forms deformation zones where they are desired, and which alsocuts the staple legs 102 to the desired lengths. Devices which can beused for such purposes can utilize means well known in the art. Theloading strip 1001 would be inserted into a suitable stapler (not shownin FIG. 10) prior to insertion of the staples 100.

FIG. 11 shows a still further embodiment of the invention whereindeformation zones are created as staples are inserted rather than priorto the use of the staples. The arrangement of FIG. 11 shows stapler jaws1102, 1103 with a staple 300 located therebetween. (Stapler jaw 1103functions as an anvil.)

Two bars 1101 are employed to form the deformation zones. The bars maybe attached to the lower jaw 1103 or the upper jaw 1102. The specifictechnique of attaching the bars is not shown in FIG. 11 for purposes ofclarity and is not material to the operation of the present invention,however means well known to the art can be used for such purpose.

When the jaws 1102 and 1103 are brought towards each other, the staple1100 will encounter the bars and bend and deform around the bags 1101.As seen in FIG. 12, the staple legs 302 will deform so that leg portions1106 and 1107 are at angles (preferably, at right angles) to each other,just as in embodiments where deformations zones are formed prior tostaple insertion.

Preferably, the anvil moves after the staple legs pass partly orcompletely through the material being stapled. After the staple has beendeformed, the bars may move aside so that the stapler can be easilyremoved, or the stapler may be set up so that the stapler can slid in adirection out of the plane of FIG. 12 to disengage from the staple.Means to accomplish such disengagement are not shown, but means wellknown to the art can be used for such purpose.

While the disclosure has mentioned the use of these staples in surgery,it is clear that such staples can find uses in other applications, e.g.,where uniform compression of the material underlying the staple isuseful or where perforation of the material would be harmful.

While particular anvils have been shown, the anvil used with theinventive staple need not be one of the anvils shown but may be anymeans of pushing the legs towards each other to achieve the deformedshape desired and may include means for stopping staple deformationafter a desired amount of deformation has occurred. Further, whilestaples with two legs have been described, it is obvious that theprinciples of the invention are applicable to staples having more thantwo legs, e.g., for applications where a larger area is intended to becompressed by each staple. Such modifications and/or additions whichfall within the spirit and the scope of the invention are intended to becovered by the following claims.

I claim:
 1. An apparatus for internal surgery comprising:a staple havinga crown and two legs, each leg being substantially perpendicular to saidcrown, each leg including a tip and having a length, each leg having anelongated deformation zone, said elongated deformation zone being aregion having a beginning and an end and extending along the length ofsaid leg, said elongated deformation zone being sufficiently long thatwhen said leg at said elongated deformation zone is deformed to a rightangle said beginning and said end do not touch one another, saiddeformation zone also being more susceptible to bending than otherregions of said less adjacent to said elongated deformation zone whensaid tips of said legs are forced toward each other; staple pusher meansfor pressing against the crown and thereby pushing said legs of saidstaples into biological tissue; and anvil means for exerting said forceson said tips of said legs parallel to said crown and in the direction ofthe other of said legs said force arising when said staple pusher meanspushes said staple such that the tips of said legs penetrate throughsaid biological tissue and against said anvil means in order to form asubstantially right angle at said elongated deformation zones.
 2. Astaple for internal surgery comprising a crown and two legs, each legbeing substantially perpendicular to said crown, each leg including atip and having a length, each leg further having an elongateddeformation zone extending along said length of said leg, each elongateddeformation zone having a beginning and an end, said elongateddeformation zone being more susceptible to bending than regions adjacentto said deformation zones of said legs when said tips of said legs areforced toward each other, said elongated deformation zone beingsufficiently long such that said leg at said elongated deformation zoneis deformed to a right angle, the beginning and the end of saiddeformation zone do not contact each other.